AT&T has announced an adjustment to its data plans for smartphone and tablet customers. Under the current plans, mobile phone and tablet users can choose to pay $15 per month for 200MB of data and $25 for 2GB. Mobile phone users also have the option of paying $45 for 4GB with mobile hotspot and tethering functionality enabled. When the new plans go into effect on Sunday, each plan gets a $5 bump in price, along with an increase in data allowance. The new plans are $20 for 300MB, $30 for 3GB, or $50 for 5GB with mobile hotspot/tethering.

Of course, those with older plans are not required to switch. AT&T allows older plans to be renewed indefinitely as long as customers don’t make changes to their data plans. Case in point, I’m still carrying around a vintage 2008 unlimited data plan on my iPhone 4S, even though the plan was discontinued in 2010. So, if you’re happy with your current data plan and want to keep it you can, provided you never need to upgrade.

The new plans go into effect on Sunday, January 22nd.